Percutaneous, ultrasound-guided introduction of medical devices

ABSTRACT

Described are methods and systems and system components useful for percutaneously delivering or retrieving vascular implant devices, such as filters, utilizing intravenous ultrasound (IVUS) imaging alone or in combination with external (e.g. transabdominal) ultrasound or other imaging technology. Implants deliverable by such systems, such as vena cava or other vascular filters, can have two or more echogenic markers spaced at such a distance that they are separately discernible by IVUS and/or external ultrasound imaging.

REFERENCE TO RELATED APPLICATION

This application is a continuation of International Application No.PCT/US2011/042670, filed Jun. 30, 2011, which claims the benefit of U.S.Provisional Patent Application Ser. No. 61/360,459 filed Jun. 30, 2010and of U.S. Provisional Patent Application No. 61/406,418 filed Oct. 25,2010, each entitled Percutaneous, Ultrasound-Guided Introduction ofMedical Devices, and each of which is hereby incorporated herein byreference in its entirety.

BACKGROUND

The present invention pertains generally to medical devices and systemsfor their introduction. In certain aspects, the invention relates tosystems and methods for percutaneously introducing vascular devices suchas vascular filters under ultrasound guidance, and to deliverycomponents and implant features that are useful therein.

Vascular devices are commonly percutaneously introduced underfluoroscopic guidance. For example, vena cava filters are most oftenplaced under fluoroscopic guidance with the injection of contrast agentto provide a cavogram characterizing the site of intended implantation.Such fluoroscopic procedures must be performed in a specially equippedroom such as an X-ray suite. This not only necessitates transport of anoften critically ill patient to the suite but also adds significantexpense to the procedure.

Ultrasound imaging technology, including intravenous ultrasound (IVUS)imaging, has been used to some extent in the diagnosis and in thetreatment of patients. However, the images generated with IVUS and otherultrasound technology are often more difficult to interpret for purposesof implant guidance, particularly for physicians or other health careproviders who are more accustomed to fluoroscopic images.

Needs exists for improved and/or alternative methods, systems and devicefeatures whereby the introduction of vascular devices such as vena cavafilters can be guided under ultrasound imaging techniques. In certain ofits aspects, the present invention is addressed to these needs.

SUMMARY

In some embodiments, the present invention relates to methods andsystems for percutaneously delivering or retrieving vascular implantdevices, such as filters, utilizing intravenous ultrasound (IVUS)imaging alone or in combination with external (e.g. transabdominal)ultrasound imaging technology. Delivery systems of the invention caninclude distally-positioned echogenic markers and proximally-positionedvisible indicia which together provide enhanced guidance during implantintroduction. Implants deliverable by such systems, such as vena cava orother vascular filters, can have two or more echogenic markers spaced atsuch a distance that they are separately discernible by IVUS and/orexternal ultrasound imaging. Additional embodiments include IVUS-enabledcatheters, IVUS-enabled sheaths, and IVUS-enabled vascular snares,useful for example in the placement or retrieval of vena cava filters,and IVUS-facilitated confirmation of device placement followingdeployment and systems therefor.

Ultrasound-guiding systems and methods described herein can utilize acombination of IVUS and external (e.g. transabdonimal) ultrasoundimages, real-time-generated images and stored images (e.g.three-dimensional maps) generated using IVUS imaging, and/or acombination of IVUS images and displayed graphical markers generated bynon-imaging techniques. Still further aspects of the invention, andfeatures and advantages thereof, will be apparent to those of ordinaryskill in the art from the description herein.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of one embodiment of a filter device.

FIG. 1A is a partial cut-away view of another embodiment of a filterdevice.

FIG. 1B is a partial cut-away view of another embodiment of a filterdevice.

FIG. 2 is a partial cut-away perspective view of one embodiment of anIVUS-enabled device delivery system.

FIGS. 3-7 illustrate devices and steps used in certain embodiments forthe delivery of a filter device.

FIG. 8-10 illustrate devices and steps used in other embodiments for thedelivery of a filter device.

FIG. 11 provides a partial cut-away perspective view of one embodimentof an echogenically-marked vascular snare in position to capture afilter device.

FIG. 12 provides a partial cut-away cross-sectional view of oneembodiment of an echogenically-marked filter device within a retrievalsheath.

FIG. 13 provides a partial cut-away cross-sectional view of oneembodiment of an IVUS-enabled filter delivery system.

FIG. 14 provides a partial cut-away cross-sectional view of anotherembodiment of an IVUS-enabled filter delivery system.

FIG. 15 provides a schematic representation of an image-guided medicaldevice delivery system.

FIG. 16 provides illustrative IVUS-generated images useful forconfirming the placement of a deployed filter device.

FIG. 17 provides a perspective view of a spring collar position markingdevice in accordance with one embodiment of the invention.

DETAILED DESCRIPTION

For the purpose of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended. Any alterations and further modificationsin the described embodiments, and any further applications of theprinciples of the invention as described herein are contemplated aswould normally occur to one skilled in the art to which the inventionrelates.

As disclosed above, certain aspects of the invention relate to methodsand systems that include features which enhance functionality and/orsafety during delivery of the vascular devices using ulstrasound imagingtechniques. Additionally, aspects of the invention relate to vasculardevices, and in particular embodiments vascular filters, including twoor more echogenic markers located thereon, as well as percutaneousdelivery or retrieval devices that include unique echogenic featuresand/or IVUS imaging capability.

With reference now to FIG. 1, shown is a vascular filter 20 in anexpanded state. Vascular filter 20 as depicted is suitable for use as avena cava filter in humans. Filter 20 includes a hub 21 having aplurality of primary struts 22 and plurality of secondary struts 23emanating therefrom. In particular, in the depicted embodiment, filter20 includes four primary struts 21 and eight secondary struts 23extending from hub 21. Hub 21 crimps together ends of struts 22 and 23in a compact bundle extending generally along a central or longitudinalaxis of filter 20. The struts 22 and 23 can be formed of a superelasticmetal alloy, such as a superelastic nickel-titanium (Ni—Ti) alloy (e.g.Nitinol), stainless steel, or any other suitable material that willresult in a self-expanding filter. The struts of filter 20 can provide afilter structure configured to trap embolic matter in the vascularvessel. Other filters of the invention can include alternate strutconfigurations or other member(s) positionable within the vessel to trapembolic matter.

Filter 20 also includes a retrievel/delivery element including agenerally straight elongate neck 24 connected to a reversely-turned hook25, with the hook terminating in ball component 26. Thisretrieval/delivery feature can be used in retrieving and/or initiallyplacing the filter 20. Although neck 24 as illustrated is generallystraight, it will be understood that other neck configurations,including curved configurations, can be used. Hub 21 includes a shoulder27 or other feature, preferably extending around its entirecircumference, that serves as an echogenic marker and thus generates anultrasound image discernable from surrounding media or devicecomponents. In addition, ball component 26 effectively serves as such anechogenic marker.

In the illustrated device, shoulder 27 and ball 26, or other echogenicfeatures in their place, are longitudinally spaced a distance “d” fromone another sufficient to enable separate and discrete visualization ofball/marker 26 and shoulder/marker 27 by IVUS imaging, externalultrasound imaging, or both. In particular embodiments, when using IVUSimaging, distance “d” is sufficiently great that the IVUS probe forgenerating the IVUS image can be positioned within longitudinal distance“d” without picking up either ball/marker 26 or shoulder/marker 27 inthe image. In this manner, the IVUS probe and other device componentsadjacent thereto (e.g. the tip of a snare catheter) can be reliably andrecognizably positioned within longitudinal distance “d” by advancing orwithdrawing the IVUS probe to separately view ball/marker 26 andshoulder/marker 27, and then positioning the IVUS probe therebetween toa point where neither marker is visible in the IVUS image. The attendingphysician or other user can thereby develop confidence that the IVUSprobe and device components nearby are properly positioned for actionwithin the span of longitudinal distance “d”. Illustratively, asdiscussed in greater detail below, a retrieval snare having an IVUSprobe at or near its distal tip can be reliably positioned withinglongitudinal distance “d” for closure of a snare loop to capture theretrieval element of filter 20. In addition or alternatively, distance“d” can be sufficiently large that marker 26 and marker 27 generateseparate and discrete images using external (e.g. transabdominal)imaging techniques. External imaging can then be used to view thepositioning of third echogenic marker, for example on another devicesuch as the end of a snare, between marker 26 and 27, for action withinthe span of distance “d”. In certain embodiments, distance “d” isgreater than 3 mm, for example in the range of 4 mm to 10 mm.

Filter 20 may also have echogenic markers positioned on one or aplurality of its primary and/or secondary struts. These echogenicmarkers can for example be echogenic elements mounted around the struts,including for example sonically-reflective metal coils discernable byIVUS or external ultrasound (US) imaging, or cannular segments withdimpled, grooved or otherwise textured surfaces, or any other suitableechogenic structure. In the illustrated device, echogenic coils 28 aremounted around the primary struts 22. Further, echogenic markers 28 caninclude projecting filaments such as whiskers or barbs 29, which canserve to enhance interaction of the struts with the vessel walls, forexample providing improved anchorage and/or resistance to strutmigration through the vessel walls.

Referring now to FIGS. 1A and 1B, shown are a partial cutaway views ofadditional embodiment of filters 20A and 20B of the invention,respectively. Except where described otherwise, filters 20A and 20B canhave features that are the same as those of filter 20. In filter 20A, adelivery/retrieval element is provided that includes a shoulder 27A onthe hub as in filter 20, and a generally straight neck portion 24Aconnected to a terminating, larger-diameter ball component 25A. Ballcomponent 25A is of sufficient dimension to serve as a graspable featureutilizing a vascular snare. Ball component 25A also serves as anechogenic marker for the filter 20A. In filter 20B (FIG. 1B), adelivery/retrieval element is provided that includes a shoulder 27B onthe hub as in filter 20, and a generally straight neck portion 24Bconnected to a terminating closed hoop 25B. Hoop 25B defines an internalopening and is of sufficient dimension to serve as a graspable feature,for example utilizing a retrieval hook device. Hoop component 25B alsoincludes at least one echogenic marker thereon and in certainembodiments a plurality of echogenic markers (25B′, 25B″, 25B′″) whichmay for example be any echogenic structure, component or materialdescribed herein, attached to or integrally occurring within or upon thematerial of hoop 25B.

While FIGS. 1, 1A and 1B illustrate specific retrieval elements forincorporation within the structure of the vascular filter, it will beunderstood that other retrieval structures or materials can also be usedwithin aspects of the invention. For example, any attachment structurethat can be engaged by mechanical elements and/or using field forces(e.g. magnetic), or by other means, can be used. In certain embodiments,as in the illustrated filters, the retrieval element of the filter canbe configured to reside generally centrally in the vessel lumen when thefilter is deployed.

With reference to FIG. 2, shown is a partial cutaway view of a systemuseful for implanting a vascular device such as a filter. System 40includes a dilator 41 for percutaneous introduction, a guide device 42such as a wire guide, and an outer delivery sheath 43. Dilator 41includes an IVUS probe 44 including one or more ultrasound transducers,such as piezoelectric crystal elements, for producing and/or receivingultrasonic sound waves. IVUS probe 44 is preferably a transducer arraywith a plurality of ultrasound transducers, but can also be provided bya single rotating transducer as known. IVUS probe 44 and other IVUSelements disclosed herein can, for example, be configured to providedata for two-dimensional and/or three-dimensional IVUS images. IVUSprobe 44 is connected electronically, such as by a wire and connector(not shown) positioned within or along dilator 41, to an IVUS imagingsystem that may include a display device and a computer processor forprocessing data gathered by IVUS probe 44 and displaying imagescorrelated thereto. Sheath 43 of system 40 includes a distal tip regionhaving an echogenic marker 45 and a fluoroscopic marker 46. Echogenicmarker 45 and fluoroscopic marker 46 can be provided by the samephysical structure or by differing physical structures.

In one embodiment, the markers 45/46 are both provided by a radiopaquematerial, such as platinum, titanium, tungsten or another a metal(including alloys), positioned outside and/or within the material makingup the body of the sheath 43. Illustratively, a platinum structure, suchas a platinum hoop or ring, can be attached around the outside of sheath43 to provide a fluoroscopically-discernible marker. Such a radiopaquestructure can also contain structural features rendering it effective asan echogenic marker. These features may for example include dimples,grooves, or other textured surface features rendering the markermaterial visually discernible by ultrasound imaging. The fluoroscopicand/or echogenic markers can also be provided by other structures ormaterials or combinations thereof. Illustratively, in one embodiment,the markers 45 and 46 can be located closely adjacent one another, withthe fluoroscopic marker 46 provided by a radiopaque material such as ametal, and the echogenic marker 45 provided by a separate element withany of the patterned features as discussed hereinabove for echogenicmarkers, or containing internal materials or features that have anacoustic impedance that significantly differs from the surrounding mediaso as to be discernible by ultrasonic imaging. The incorporated featuresor materials can include for example gas-filled spaces embedded withinpolymeric materials (e.g. bubbles), or acoustic impedance-mismatched,sonically-reflective materials such as glass, ceramic, metal or otherparticles (e.g. beads) incorporated within or coated upon a polymericmaterial. For additional information about echogenic markers that can beused herein, reference can be made for example to U.S. Pat. No.5,201,314.

The markers 45/46 can be associated with sheath 43 in any suitablefashion including positioning on the outside, inside, within the body orwall of the sheath 43, or combinations thereof. Sheath 43 also includesa more proximally located marking feature 47 that is visible to the eyeof the user when positioned externally of the patient. Visible markingfeature 47 in the illustrated embodiment demarks the distance fromlocations within feature 47 to the distal tip of the sheath 43. Forthese purposes, the marking feature 47 can include a plurality ofvisible marking features 48 spaced longitudinally from one another alongthe length of sheath 43, such as lines, scores, or other markingspartially or completely circumscribing the circumference of the sheath43. In the illustrated embodiment, the marking feature 47 also includesnumeric markings 49 associated with markings 48 which numericallyindicate the distance of the respective associated markings 48 from thetip of the sheath 43. In one example, the marking feature 47 includesmarkings 48 offset longitudinally from one another by a regular distancesuch as 1 mm or 1 cm, and associated numerical markings 49 providing anindication of how many millimeters or centimeters, respectively, eachmarking 48 is spaced from the distal tip of the sheath 43. The markingfeature 47 is positioned along the length of the sheath 43 such that atleast some of or the entire marking feature 47 will occur externally ofthe patient during use of the sheath 43 to deliver the filter or othervascular device. For these purposes, the marking feature 47 can forexample be positioned so as to include markings at skin level at apercutaneous insertion site through which system 40 is introduced. Inthis regard, it will be understood that other reference points externalof the patient against which the marking feature 47 can be reliablytracked during a procedure to determine the distance to the distal tipof the sheath may also be used. Fixed external reference points areparticularly useful for these purposes.

In one mode of use, the IVUS-enabled dilator 41 can be advanced within avascular vessel of the patient along guide 42, and the IVUS probe 44 canbe operated to generate signals translated to images of features of thevessel. IVUS probe 44 can then be positioned to and image a targetposition to which it is desired to move the distal tip of the sheath 43.Thereupon, the sheath 43 can be advanced coaxially along the dilator 41until the distal tip of the sheath 43 detectably abuts or overlies IVUSprobe 44 or regions proximate thereto. This detection can, for example,be by way of a tactile resistance to advancement of the sheath 43 overthe IVUS probe 44 or some region or feature of sheath 43 proximatethereto, or by a change in an ultrasound image generated based signalsfrom IVUS probe 44 due to the distal tip of the sheath 43 overlying someor all of IVUS probe 44 (for example, a change in the brightness of theimage). This change in the image, in certain embodiments, can beenhanced by the presence of the echogenic marker 45 at the distal endregion of sheath 43. At this point, the user knows that the distal tipof the sheath 43 is in essentially the same target position as the IVUSprobe 44. Thereafter, the dilator 41 and guide 42 can be withdrawn fromsheath 43, and a delivery catheter or other delivery instrument fordelivering the vascular device can be advanced through sheath 43, whilecontinuing to hold stable the position of the sheath 43 with its distaltip at the target position. In certain embodiments, the distal tip ofthe vascular implant to be deployed can then be aligned with the distaltip of the sheath 43 while maintaining the stable position of the sheath43, and sheath 43 can be withdrawn proximally a distance while holdingstable the position of the delivery instrument to reliably deploy thevascular device at the target site.

The alignment of the distal end of the vascular implant with the distalend of the sheath 43 can be accomplished in any suitable manner,including by tracking the position of the distal tip of the vascularimplant ultrasonically (e.g. transabdominally with the assistance of atip-located echogenic markers, such as marker 26 on filter 20 and marker45 on sheath 43) and/or through other means. In certain embodiments, thevascular device is carried by a delivery catheter or other instrumenthaving a first visible marker that remains external of the patient andwhich aligns with an external reference point, such as the proximal endof the sheath 43 or a connected accessory (e.g. a Touhy-Borst adaptor),when the distal end of the vascular implant is at the distal tip of thesheath 43. The delivery instrument may also include a second visiblemarker, proximal to the first visible marker, to which the sheath can bewithdrawn, to signal a stage of deployment, e.g. when the vascularimplant has been completely deployed out of the sheath. Other measuresfor accomplishing similar signaling alignments may also be used.

The use of system 40 of FIG. 2 to deliver a vena cava filter to apatient will now be described with reference to FIGS. 3-7. FIG. 3 showssystem 40 having been introduced into the vena cava 50 through apercutaneous access site 51 in the right femoral vein of a patient.Right renal vein 52A and left renal vein 52B feed into the vena cava 50,and in the illustrated embodiment it is desired to deploy a filtergenerally below the renal veins 52A and 52B, or “caudal” thereto.Depicted in FIG. 3 is dilator 41 advanced into vena cava 50 and at aposition at which IVUS probe 44 can generate an image of at least thelowest-positioned renal vein, in most instances that being the rightrenal vein 52A. Prior to reaching this position, the IVUS probe 44 canbe used to generate images of vascular landmarks distal to the renalveins, for example the right atrium, the hepatic veins, or otherfeatures. In certain embodiments the IVUS probe 44 will have alongitudinal resolution such that an image showing both renal veins 52Aand 52B can be obtained. Sheath 43 is also percutaneously inserted intothe vena cava, which insertion may have been before, with, or after thatof dilator 41. The distal tip of sheath 43 is shown positioned wellbelow the IVUS probe 44 so that it does not obscure IVUS probe 44 andthereby degrade generated image data. As can also be seen, the markingfeature 47 includes at least portions remaining at skin level on thepatient, and demarking the shaft distance from skin level to the distaltip of sheath 43. Further, in the illustrated embodiment, arepositionable scale marker 54 is positioned about sheath 43 and can beadvanced to locations within marker feature 47. Scale marker 54 caninclude a stop or locking mechanism 55 which can be actuated toselectively release and secure the position of scale marker 54 alongsheath 43. Any suitable mechanism can be used for this purposeincluding, for example, spring actuated friction stops against thesheath 43, tightenable screws or knobs which abut sheath 43 or cinchmarker 54, or the like.

Referring to FIG. 17, the marker 54 can comprise a spring collar 54A,which itself represents another aspect of the invention, receivablearound the sheath 43 (see illustrative FIG. 3B; it will be understoodthat spring collar 54A can also be used as marker 54 in other FIGs. inwhich marker 54 is shown). Spring collar 54A includes a wire spring 120with a wire coiled to provide one or more wire loops and preferably aplurality of wire loops 121, which can be positioned adjacent to oneanother. Spring collar 54A can also include a first wire segment 122extending from the wire loop(s) 121 and a second wire segment 123extending from the wire loop(s) 121. In a relaxed (unstressed)condition, the segments 122 and 123 extend in directions that areradially offset from one another about a central axis “A” of the wireloop(s) 121, preferably at an offset of less than about 140 degreesabout central axis “A”. The spring collar 54A is configured such thatthe segments 122 and 123 can be moved radially toward one another, forexample by squeezing them toward one another, to cause the internaldiameter of the wire loop(s) 121 to increase in size in the resultingstressed condition of the spring collar 54A. In this fashion, springcollar 54A can be received around sheath 43 or another elongate,percutaneously introduced device, and can be sized to frictionallyengage the outer surface of the sheath 43 or other device when in itsrelaxed condition or at least biasing toward its relaxed condition, andthen frictionally disengage (or at least engage with less friction) whensegments 122 and 123 are moved toward one another to increase theloop(s) diameter. This action can be used to facilitate repositioningthe spring collar 54A along the sheath 43 or other device bydisengaging, moving and then re-engaging the spring collar 54A. Otheractions that reduce the diameter of loop(s) 121 may also be used,including for instance an action in which moving segments 122 and 123toward one another causes such diameter to decrease while introducingstress into the spring collar. In such a design, for frictionalengagement with the sheath 43 or other device, a feature for holding thesegments 122 and 123 in position once the sheath/device is stressed andthereby engaged could be used, for example a clip or cap. The clip, capor other feature could thereafter be removed or released to disengagethe spring collar from the sheath 43/device, move the spring collar, andthen re-applied after squeezing segments 122 and 123 toward one anotherto re-engage the sheath/device.

As illustrated in FIG. 17, the spring collar 54A can optionally includea molded plastic or other jacket attached to and that at least partiallycovers the wire spring 120. Such a jacket can be provided by one pieceor optionally multiple pieces, and desirably includes at least tabportions connected respectively to each of the wire segments 122 and123, with the tab portions providing a widened (relative to thediameters of the wire segments 122 and 123) area that can be used formanually gripping and manipulating the spring collar 54A for theengagement/disengagement operations discussed above. In the illustratedembodiment, the jacket includes a first jacket piece 124 and a secondjacket piece 125. First and second jacket pieces 124,125 includerespective tab portions 126,127 which define respective grooves 128,129for receiving respective portions of wire segments 122,123. Grooves 128and 129 terminate along the lengths of tab portions 126 and 127, and tabportions 126 and 127 include portions 130 and 131 outward of the grooves128 and 129 which define respective apertures 132 and 133 for receivingoutward end portions of the wire segments 122 and 123. If desired, abonding agent can be applied within apertures 132 and 133 or at otherlocations to help to secure the jacket pieces 124 and 125 to the wirespring 120. Jacket pieces 124 and 125 can also include structures forjacketing the wire loop(s) 121 of the wire spring 120. With reference tofirst jacket piece 124, it includes a loop-covering portion 134 thatincludes one or more fingers 135, preferably two or more fingers. Secondjacket piece 125 includes a loop covering portion 136 that includes oneor more fingers 137, preferably two or more fingers. When jacket pieces124 and 125 are assembled on the wire spring, finger(s) 135 andfinger(s) 137 interleave but remain slidably disposed with respect toone another. In this fashion, when tab portions 126 and 127 are squeezedor otherwise forced toward one another to enlarge the loop(s) 121,finger(s) 135 and 137 will slide relative to one another so as todecrease their extent of interleaved overlap while still providing astructure that generally surrounds the loop(s) 121. Release of the tabportions 126 and 127 will then cause finger(s) 135 and 137 to slideagain relative to one another so as to increase their extent ofinterleaved overlap while providing a loop(s)-surrounding structure.Jacket portions 124 and 125 can optionally each be monolithic pieces, asillustrated, providing both the respective tab portions andloop(s)-surrounding portions.

When the spring collar 54A or other scale marker 54 is frictionallyengaged with the sheath 43 or other device, it can do so whilecompressing the sheath 43 or other device at a level which does notsubstantially deform the shape of the sheath 43 or other device (e.g.leaving open an internal lumen thereof) but which creates sufficientfriction to resist movement of the collar 54A or other marker 54 alongthe sheath 43 or other device during use. For example, such friction canbe sufficient to require a force of greater than 2 Newtons applied tothe engaged collar 54A/marker 54 in the direction of the longitudinalaxis of the sheath 43 or other device in order to cause sliding movementof the engaged collar 54A/marker 54, more preferably in the range ofabout 3 Newtons to 10 Newtons, and most preferably about 4 to about 5Newtons. It will be understood that other force values could be utilizedin varied circumstances depending for instance upon the particularpercutaneously-introduced device and procedure requirements associatedtherewith. It will also be understood that the friction and resultantresistance to linear displacement of the engaged spring collar 54A orother marker 54 can depend, for instance, upon the extent of surfacecontact, the surface characteristics and materials of construction ofthe collar or marker and those of the sheath or other percutaneousdevice, which can also be varied in achieving the desired result. Thevariation of these and other parameters will be within the purview ofthose skilled in the field given the teachings herein. Moreover, asshown in FIG. 3C, in accordance with certain inventive embodiments, aspring collar 54A or other biased marker 54 can be equipped with aretainer device 54B that holds the collar 54A or other marker 54 in anunrelaxed (or stressed) condition when received around the sheath 43 orother device. For example, the sheath or other device can be packaged orhandled with the collar 54A or other marker 54 received therearound, butequipped with the applied retainer device 54B to disengage or reducecompression of the sheath 43 or other device by the collar 54A or othermarker 54. In this fashion, potential deformation of the sheath 43 orother device over time, e.g. during storage prior to use, can be reducedor eliminated. As illustrated, retainer device 54B can be a cap in whichtab portions 126 and 127 are received and held closer together than theywould be in a relaxed condition of the collar 54A, although otherretainer elements or devices that resist return of the spring collar 54Ato its relaxed condition could also be used.

Returning to a discussion of an illustrative procedure, with particularreference to FIG. 4, while holding the position of IVUS probe 44stationary, sheath 43 is advanced coaxially over dilator 41 until thedistal tip of sheath 43 advances over IVUS probe 44. This event can besensed tactilely as discussed above, and/or through a change in theimage generated by IVUS probe 44 due to being covered by the wall ofsheath 43 (potentially enhanced by the presence of echogenic marker 46,which can be configured to reflect ultrasonic energy sourced from theprobe 44 within). At this point, the user knows that the distal tip ofsheath 43 is positioned at the target position found with the IVUS probe44. The user can then reference the scale markings within the markingfeature 47 that coincide with the skin level of the percutaneousinsertion site 51. A correlation can thereby be drawn between thepositioning of the distal tip of the sheath 43 at the target site and ascale marking within marking feature 47. Again, in one embodiment, suchscale marking includes a numeric value correlating to the distance fromthe marking to the distal tip of sheath 43. The repositionable scalemarker 54, when present, can also be advanced and secured to abut thepercutaneous insertion site 51 with the distal tip of sheath 43 at thistarget position. The dilator 41 and if still present the wire guide canthen be removed from the sheath 43 while holding the sheath stably inposition with the distal tip of the sheath 43 at the target position.

Referring now to FIGS. 5 and 6, thereafter, a filter introducer systemcarrying filter 20 (FIG. 1) is advanced into the sheath 43. In FIG. 5,shown is filter introducer system 60 advanced into sheath 43 to positionthe distal tip of filter 20 substantially at the distal tip of sheath43. As noted above, this positioning can be discerned in any suitablemanner. In the embodiment shown, filter introducer 60 includes proximal,visible markers 62 and 63 spaced longitudinally from one another, andpositioned on introducer 60 so as to remain external of the patientduring the procedure. When the distal-most marker 62 aligns with adistal-most portion of the sheath 43, or aligns with anotheridentifiable reference associated with sheath 43, the distal tip offilter 20 is aligned with the distal tip of sheath 43.

With reference now to FIGS. 5 and 6 together, at this point, sheath 43can be withdrawn until the proximal end of sheath 43 (or the associatedreference point) is flush with marker 63, whereupon filter 20 isexternalized from sheath 43 at the target location. In the illustratedembodiment, at this stage, the secondary legs 23 of filter 20 aredeployed outwardly against the wall of the inferior vena cava 50;however, the primary struts 22 remain engaged by retaining element 61,such as a metal mount, located at the tip of introducer 60. Retainingdevice 61 is actuatable from a position external of the patient torelease primary struts 22 of filter 20, for example by operating abutton, switch, lever, or any other suitable mechanism. Such a mechanismis in use at present on the COOK® CLECT® filter set for femoral veinapproach (William Cook Europe, Denmark), which mechanism can be usedherein. Additionally, reference can be made to U.S. Pat. No. 5,324,304,which describes similar release mechanisms that can be used herein.

After release of the primary struts 22 from the retaining element 61,filter 20 fully deploys in vena cava 50, and sheath 43 and any otherpercutaneously introduced devices can thereafter be withdrawn from thepatient. Shown in FIG. 7 is an enlarged view of filter 20 as deployedwithin the inferior vena cava 50, with both secondary struts 23 andprimary struts 22 having expanded radially outwardly against the wall ofvena cava 50. With filter device 20 so deployed, in certain embodimentsthe echogenic markers 26 and 27 are sufficiently spaced to be viewed bytransabdominal ultrasound as distinct images. Still further, indesirable embodiments, echogenic markers 28 are located on primarystruts 22 so as to be positioned against the caval or other vessel wallwhen in the expanded, deployed condition. The position of echogenicmarkers 28 and thus of the associated strut regions can thus beconfirmed with ultrasound images. As noted above, the elongate generallystraight filaments 29 extending from markers 28 can aid in the fixationof device 20 against the walls of vena cava 50 and/or can help toprevent migration of the struts 22 through the caval or other vesselwall.

In advantageous operations, after deployment of the filter 20 fromsheath 43 and release of the primary struts 22 from retaining device 61,the filter introducer 60 is withdrawn while leaving sheath 43percutaneously inserted. The guide 42 can then be reinserted throughsheath 43 and an IVUS-enabled catheter such as dilator 41 can bereintroduced over the guide 42. With the guide 42 extending into orbeyond the filter 20, the IVUS-enabled dilator 41 can be advanced withinvena cava 50 and the IVUS probe 44 can be used in the generation ofimages to confirm the deployment position of filter 20. In one mode, theIVUS images generated can be used to inspect the position of the primarystruts 22 and/or secondary struts 23 against the wall of vena cava 50.To facilitate this inspection, echogenic markers (e.g. 28) positioned onstruts 22 and/or 23 and configured to be apposed against the wall ofvena cava 50 upon proper deployment of the filter 20 can be used togenerate images from which such apposition can be confirmed or denied.The IVUS probe 44 can also if desired be advanced beyond filter 20 togenerate an image of renal vein or veins 52A and/or 52B to confirmposition of the filter 20 caudal thereto. After this inspection, andpotentially also electronic storage of the confirming images for thepatient record, the guide device 42 and IVUS-enabled dilator 41 can bewithdrawn from the patient. For example, shown in FIG. 16 are images ofa vena cava filter implanted in the vena cava of a sheep, obtained byadvancing an IVUS-enabled catheter beyond the implanted filter andgenerating IVUS images during a pull-back of the catheter. Shown at thetop is a projection image generated from a series of axial images,depicting the lower renal junction, the vena cava filter hook, thefilter legs, and the ilio-caval bifurcation. The projection image hasinterpretive markings added by the user, in the form of color-codedvertical lines corresponding to anatomical landmarks and features of theimplanted device. Desirably, the projection image or otherIVUS-generated image(s) will depict the first and second ends of thedevice, which can optionally be marked on the image by the user. Shownat the bottom are axial IVUS images corresponding to the device featuresand anatomic landmarks discussed above and depicted in the projectionimage, and color coded to the vertical lines added to the projectionimage. These and other marking and/or indexing measures can be taken toadd clarity to the interpretation of the image(s). Such an image orimages can be obtained of an implanted vena cava filter or othervascular filter or other device, with accompanying physiologic landmarksfrom the patient, to confirm proper placement of the device followingdeployment. The optional presence of echogenic features on the device,e.g. on the filter hook and/or filter legs, can enhance the ability tovisualize the device features in the confirming ultrasound images. Theutilization of IVUS-generated device placement images to confirm thelocation of the implanted device after deployment, and for purposes ofmaintaining a patient medical record relating to the surgery,constitutes another embodiment of the invention and can be used inconjunction with any system or placement method described herein orotherwise. The collected IVUS data can be filtered to improve the IVUSimage, for example by excluding data from certain segments or regions.For example, the projection image in FIG. 16 (top) was generated fromdata taken from the longitudinal volume depicted between the dottedlines in the left-most axial image found below. This technique and/orother filtering techniques can be used to improve the image qualitygiven the teachings herein. The IVUS-generated images can beelectronically stored in the patient record, e.g. using a data captureand storage system directly coupled to the IVUS device or system, or byotherwise transferring the electronic data to the patient record, and/orby retaining printouts or other “hard copy” version of the capturedconfirming images. In certain embodiments, the IVUS-generated image canserve as an alternative to any radiographic image (e.g. X-ray image)where no radiographic confirmation of placement is taken, and in otherembodiments the IVUS-generated image can serve as an addition to aplacement-confirming X-ray or other radiographic image in the patientrecord.

FIGS. 7-9 illustrate an embodiment of a delivery system for a vasculardevice, such as a vascular filter, that is useful from an approachdescending downwardly within the vena cava, e.g. through a percutaneousaccess site in the left or right jugular vein. System 70 has numerousfeatures which correspond directly with features of system 40 discussedabove, to which reference can be made for details. System 70 includes anIVUS-enabled dilator having an IVUS probe 78, for percutaneous insertionthrough percutaneous access site 71. System 70 includes a sheath 72translatable coaxially over the dilator. An echogenic marker 73 isprovided at the distal end of sheath 72. Sheath 72 further includes anechogenic marker 74 spaced proximally of marker 73 a longitudinaldistance 75. Markers 73 and 74 can optionally include physicallydiscrete or physically integrated fluoroscopic markers as discussedabove. Longitudinal distance 75 corresponds to a desired distance foradvancement of the distal tip of sheath 72 beyond IVUS probe 78 toposition the sheath for deployment of a vascular device, as discussed infurther detail below. Sheath 72 also includes a marking feature 76corresponding to marking feature 47 of sheath 43, desirably a numericdistance scale, as discussed above. It will be understood in this regardthat the relative position of marking feature 76 along sheath 72 maydiffer from the position of marking feature 47 along sheath 43, due tothe differing distances from the respective percutaneous entry sites thetarget site. System 70 also includes a guide device 79 such as a wireguide. Shown in FIG. 7 is the dilator with the IVUS probe 78 in positionto image and identify a location at or just below the renal veins 52Aand 52B which feed into inferior vena cava 50. This position is intendedto be at or near the uppermost portion of the vascular implant whendeployed. Sheath 72 is shown in FIG. 7 in position with its distal tipproximal of IVUS probe 78 for best viewing conditions.

Referring now particularly to FIG. 8, while holding the IVUS probe 78 inthe target position, sheath 72 has been advanced along the dilator. Indoing so, the advancement of the distal sheath tip over the IVUS probe78 is recognizable by the user by a change in the generated IVUS image,which can be enhanced through the presence of an echogenic marker 73. Asthe sheath 72 is advanced further, the user will again note a change inthe IVUS image as the more proximal echogenic marker 74 arrives overtopthe IVUS probe 78. If desired, sheath 72 can be configured to alsoprovide a tactile signal of this positioning. In this position, thedistal tip of the sheath 72 has been advanced to a target locationdistal of the IVUS probe 78 from which pull-back of sheath 72 will beinitiated for deployment of the implant. At this point also, the usercan make visual reference to the visible marker feature 76 and in aparticular embodiment to scale markings therein which align at skinlevel at the percutaneous entry site 71, or with any other suitablelocation correlating to the position of the distal tip of the sheath 72.While holding the sheath in position, potentially with continuingreference to the position of scale markings within the marking feature76, the dilator including IVUS probe 78 and the guide 79 can then bewithdrawn.

With reference now to FIG. 9, a filter introducer 80 carrying filter 20can then be inserted through sheath 72. Filter 20 can for example beheld by introducer 80 with a loop, hook or similar retaining device 84located at the distal end of introducer 80 and engaging the hook offilter device 20. Similar to system 40 above, filter introducer 80includes proximally-positioned external visible markers 82 and 83 spacedlongitudinally along the shaft of device 80. The distal marker 82 alignsgenerally with a reference point, for instance the proximal end ofsheath 72 or an element connected thereto, when the distal end of filter20 is generally aligned with the distal tip of sheath 72. Afteradvancing filter introducer 80 to this position while holding sheath 72in place, sheath 72 can be withdrawn proximally until the distal end ofsheath 72 (or piece associated therewith) is generally flush with marker83, giving indication that the filter device 20 has been deployed fromthe distal opening of sheath 72. Retaining device 84 can then beactuated to release filter device 20 from introducer 80, thus leavingfilter device 20 deployed within the inferior vena cava. Thereafter, ifdesired, the guide device 79 and the IVUS-enabled dilator can bere-introduced through sheath 72 and used to inspect the deployed filter20 and the apposition of its struts against the caval wall. Echogenicmarkers 28 positioned on the primary struts 22 and/or the secondarystruts 23 can facilitate capturing images showing those markers at oragainst the wall of vessel 50 to provide assurance that the filter 20has properly and completely deployed. The guide 79, the dilator withIVUS probe 78 and if still present the sheath 72 can then be withdrawnfrom the patient.

In additional aspects of the invention, provided are IVUS-enabled and/orechogenically-marked percutaneously-insertable devices that can be usedin the retrieval or delivery of vascular filters or other implantdevices. FIG. 11 is a partial cut-away view of a percutaneous vascularsnare device 90 embodiment of the invention. Vascular snare 90 includesan elongate shaft 91 having an internal lumen and a snare loop 92, forexample made of a flexible filament(s) such as wire, which can becontrollably deployed from and withdrawn into the lumen. Snare device 90includes an echogenic marker 92 on at least a portion of the snare loop92. Echogenic marker 92 can include a grooved structure, a coil such asa wire coil, a dimpled and/or grooved structure such as dimpled and/orgrooved cannula, or any other suitable echogenic structure or materialas discussed herein. Further, marker 92 can be mounted over the wire orother elongate filament forming the snare loop 92, or can be integrallyformed into the wire or other elongate filament. Echogenic marker 92 issized and configured to permit the deployment of the snare loop 92smoothly out of and into the canulated device 91 without substantialdamage to either, so as to facilitate capturing devices with the snare.In certain embodiments, the snare device 90 includes an IVUS probe 94.The IVUS probe 94 can be used in obtaining ultrasound-generated imagesof a device to be captured and potentially retrieved with snare device90. Still further, in some embodiments, the echogenic marker 93 of snaredevice 90 can be positioned on the snare loop 92, and the snare loop candeploy to a configuration, such that at least a portion of the marker 93can be imaged using an ultrasonic signal generated with the IVUS probe94. For these purposes, the snare loop 92 can deploy, at least in part,laterally from the lumen of the cannulated device 91, so as to positionat least a portion of the echogenic marker 93, and potentially theentire marker 92, within the range of longitudinal resolution of theIVUS probe 94. In this manner, a user of snare device 90 can confirmdeployment and position of the snare loop 92 in an open position byviewing images generated with IVUS probe 94. For these purposes, thesnare loop 92 can be deploy to an open condition in which at least aportion of echogenic marker 93 aligns longitudinally with at least aportion of IVUS probe 94, or is longitudinally offset no more than about3 mm therefrom. Echogenic marker 93 can, of course, also be visualizedusing an externally-generated (e.g. transabdominal) ultrasound image, toassist in guiding a capture or retrieval operation. Such externalultrasound imaging can also be used in conjunction with IVUS imagingderived from IVUS probe 94 in guiding the operation.

With continued reference to FIG. 11 and also to FIG. 12, in one mode,vascular snare 90 can be used to capture and retrieve an implantedvascular filter, for instance filter 20 described herein. External (e.g.transabdominal) ultrasound imaging can be used to discretely visualizeechogenic markers 26 and 27 of filter 20 and echogenic marker 93 ofsnare device 20 (in an open condition) positioned therebetween andaround neck 25 of filter 20. Snare loop 92 can then be closed bywithdrawing it into the cannulated shaft 91 so as to capture filter 20,with the closed snare loop ultimately catching in hook 25. Alternativelyor in addition, when IVUS probe 94 is present, vascular snare 90 can beused in generating an IVUS image to discretely and sequentiallyvisualize marker 27 and marker 26 of filter 20, to guide positioning ofthe snare loop therebetween and around the neck 25 of the filter 20,whereupon it can be closed to capture the filter 20. After capture ofthe filter in the snare loop 92 in a closed condition, a cannulatedretrieval device 95 (FIG. 12) such as a catheter or sheath can beadvanced over device 91 and over filter 20 to force struts 23 and 22radially inwardly to retrieve the filter 20 into the cannulatedretrieval device 95. The snare 90, filter 20 and cannulated retrievaldevice 95 can then be removed from the patient. Alternatively, such acapture and/or retrieval operation can be used to reposition the filter20 after deployment.

FIG. 13 illustrates another embodiment of an IVUS-enabled filterdelivery system 100 of the invention. System 100 includes a filterdelivery sheath 101 with filter 20 housed in a lumen thereof. Deliverysheath 101 can have all of the attributes of sheath 43 discussedhereinabove, including but not limited to marking feature 47 andrepositionable scale marker 54 (see, e.g., FIGS. 2-6). Delivery sheath101 also has an IVUS probe 102 mounted proximate its distal tip. Asdiscussed above, wire(s) and connectors for powering IVUS transducerelement 102 and for transmitting signal data can be suitably routedalong sheath 101 embedded within shaft walls, within additional lumensthereof, or properly positioned and protected, may share a lumen withfilter 20. Any of these same arrangements or combinations thereof can beused for routing wire(s) and connectors for any of the IVUS probesdisclosed herein. The presence of IVUS probe 102 on the implant deliverysheath 101 itself can eliminate the need to use a separate IVUS-enableddevice (e.g., the IVUS-enabled dilator 41 discussed above), although incertain modes of use both types of IVUS-enabled devices could be used inguiding the device delivery.

Delivery sheath 101 also includes an echogenic marker 103 and/or afluoroscopic marker 104. As discussed above, markers 103 and 104, whenboth present, can be provided by a single structure or material withdual function, or by separate pieces or structures. The arrangementsdiscussed above can be suitably used. IVUS-enabled filter deliverysystem 100 also includes a filter introducer device 105, such as acatheter, having an elongate shaft 106 and a retaining element 107, suchas a metal mount, in which the ends of primary struts 22 of filter 20are received, and are releasably held. The ends of primary struts 22 canbe released from retaining element 107 upon actuation of a button,switch or other suitable mechanism of introducer device 105, asdiscussed above for other embodiments.

Delivery sheath 101 can be used to percutaneously deliver vena cavafilter 20 to a position generally as shown in FIGS. 3-6, withmodification. To do so, sheath 101 can be percutaneously introduced(conventionally along with a dilator, which is then removed), e.g.through the right or left femoral vein, and advanced to a position toview the renal veins using the IVUS probe 102. With the position of theprobe 102 generally at or caudal to the lower renal vein (typically theright), the position of the sheath 101 can be noted (e.g. using visiblescale markings corresponding to feature 47 above). Holding the sheath101 in place, the filter introducer 105 can be used to advance the hookof filter 20 to the distal tip of the sheath 101, for example usingalignment of external, visible proximal marker 108 on introducer 105with a feature on or associated with sheath 101 to signal that thedistal tip of filter 20 is aligned with the distal tip of sheath 101.The position of the distal tip of sheath 101 within the inferior venacava can then be confirmed using the external (e.g. skin-level) visiblescale markings on the sheath and/or using the IVUS probe 102 tovisualize the renal vein(s) again. The sheath can then be pulled back toalign the feature on or associated with sheath 101 with external,visible marker 109 to signal that filter 20 has been deployed from thedistal opening of sheath 101. The release actuator for retention device107 can then be operated to release primary struts 22 of filter 20 tofully deploy the filter 20.

FIG. 14 illustrates still another embodiment of an IVUS-enabled filterdelivery system 110 of the invention. System 110 includes a filterdelivery sheath 111 with filter 20 housed in a lumen thereof. Deliverysheath 111 can have all of the attributes of sheaths discussedhereinabove, including but not limited to external visible markingfeatures (e.g. 76, FIGS. 8-10) and a repositionable scale marker (e.g.54, FIGS. 2-6). Delivery sheath 111 also has an IVUS probe 112 adistance proximal to its distal tip. The presence of IVUS probe 112 onthe implant delivery sheath 111 itself can eliminate the need to use aseparate IVUS-enabled device (e.g., an IVUS-enabled dilator as discussedabove), although in certain modes of use both types of IVUS-enableddevices could be used in guiding the device delivery.

Delivery sheath 111 also includes an echogenic marker 113 and/or afluoroscopic marker 114 proximate its distal tip, the construction ofwhich can be as discussed hereinabove. System 110 also includes a filterintroducer device 115, such as a catheter, having an elongate shaft 116and a retaining element 117, such as a hook, releasably engaging thehook of filter 20. The hook of filter 20 can be released from retainingelement 117 upon actuation of a button, switch or other suitablemechanism of introducer device 115, as discussed above for otherembodiments.

Delivery sheath 111 can be used to percutaneously deliver vena cavafilter 20 to a position generally as shown in FIGS. 8-10, withmodification. To do so, sheath 111 can be percutaneously introduced(conventionally along with a dilator, which is then removed), e.g.through the right or left jugular vein, and advanced to a position toview the renal veins using the IVUS probe 112. With the position of theprobe 112 generally at or caudal to the lower renal vein (typically theright), the position of the sheath 111 can be noted (e.g. using externalvisible scale markings corresponding to features 47 or 76 above). Due tothe distance between IVUS probe 112 and the distal end of sheath, thisposition will place the distal end of sheath 111 well caudal the renalvein(s), at a position corresponding to the desired lowermost point ofthe deployed filter implant. In the illustrated embodiment, the distancefrom IVUS probe 112 to the distal sheath tip is approximately equal toor slightly greater than (e.g. up to about 130% of) the length of filter20 when deployed. Holding the sheath 111 in place, the filter introducer115 can be used to advance the distal leg ends of filter 20 to thedistal tip of the sheath 111, for example using alignment of external,visible proximal marker 118 with a feature on or associated with sheath111 to signal that the distal tip of filter 20 is aligned with thedistal tip of sheath 111. The position of the distal tip of sheath 111within the inferior vena cava can then be confirmed using the external(e.g. skin-level) visible scale markings on the sheath and/or using theIVUS probe 112 to again visualize the renal vein(s). The sheath can thenbe pulled back to align a feature on or associated with sheath 111 withexternal, visible marker 119 to signal that filter 20 has been deployedfrom the distal opening of sheath 111. The release actuator forretention device 117 can then be operated to release the hook 25 offilter 20 to fully deploy the filter 20.

In additional embodiments, unique ultrasound image guidance methods andsystems are provided. These methods and systems can be used inconjunction with implant devices and delivery/retrieval componentsdiscussed hereinabove, or with other devices or components. In oneaspect, ultrasound guidance of percutaneous procedures can be providedusing a combination of real time IVUS images and electronically-storedimages. The electronically-stored images can, for example, be sequentialimages of a vessel acquired during pull-back of an IVUS probe (e.g., onIVUS-enabled dilators, sheaths or snares as discussed above) within thevessel, desirably at a constant speed, or generated images reconstructedfrom a plurality of such sequential images. Constant-speed pull-backdevices for these purposes are known and commercially available. Thegenerated, stored images can for example be three-dimensional ortwo-dimensional images of the length of vessel in which an implant suchas a filter is to be deployed, reconstructed from a plurality ofsequential, cross-sectional or otherwise segmental images of the vessel.

With reference to FIG. 15, provided is a schematic showing components ofone embodiment of such a system. System 200 as depicted includesIVUS-enabled dilator 41 as described above (FIGS. 2-4), although otherIVUS-enabled devices such as the dilator of FIGS. 8-9, snare 94 (FIG.11) or delivery sheaths 101 (FIG. 13) or 111 (FIG. 14) can besubstituted for dilator 41. Dilator 41 includes IVUS probe 44 and alsoincludes a marking feature 47A, which can be the same as marking feature47 discussed hereinabove in connection with FIGS. 2-6) and thus includeindividual scale markings 48 denoting a distance from the marking to adistal feature of dilator 41, such as the distance from the individualscale marking to the IVUS probe 44, and associated numerical markings49. Dilator is shown percutaneously inserted with scaled regions ofmarking feature 47A occurring at skin level at entry site 51 on thepatient.

System 200 includes a computer processor 201, which can also include anelectronic memory storage for storing data and images. Computerprocessor 201 receives signal data from IVUS probe 44 via datatransmission connection 202, which can for example be a wired orwireless connection. Computer processor 201 generates ultrasound imagesof vessel 50 using the transmitted signal data. Processor 201 iselectronically connected via connection 203 to a visual display device204 such as a display monitor. Display device 204 displaystwo-dimensional, real time IVUS images 205 generated using IVUS probe44. In the depicted image 205, shown are the left and right renal veinsgenerated by IVUS probe 44 positioned closely thereby. Display device204 also displays an image 206 generated by reconstructing a pluralityof previously-acquired two-dimensional, cross-sectional image data setsfrom IVUS probe 44. Algorithms for these purposes are known and are alsoavailable in commercially available IVUS devices and associatedsoftware, including those available from Volcano Corporation (San Diego,Calif., USA). The previously-acquired data sets for reconstructing image206 can be obtained during a pull-back of dilator 41, desirably atconstant speed, during which IVUS image data are collected, desirably atregular time intervals. A pull-back device 206A can be used for thesepurposes, embodiments of which are also commercially available fromVolcano Corporation.

In one embodiment, a graphical scale 207 is displayed on or inconjunction with image 206. Scale 207 can have scale markings 208 whichcorrelate to individual scale markings 48 on dilator 41. Scale 207 canalso have respective associated numerical markings 209 which correlateto respective associated numerical markings 49 on dilator 41. Thus, forexample, a scaled marker on graphical scale 207 that is numbered “10 cm”will align longitudinally on or next to image 206 at a point correlatedto the longitudinal position of IVUS probe 44 when a corresponding “10cm” scaled marker of marking feature 47A occurs at skin level of entrysite 51. Reliable external reference points for marking feature 47Aother than skin level could also be used. In one manner of generatingand locating graphical scale 207, at the starting point for pull-back, auser can input to the processor 201 the numeric indicia 49 havingassociated marker 28 at skin level. Using time-elapsed andconstant-speed information provided to processor 201 by pull-back device206A via connection 206B, processor 201 can ascertain how far probe 44has traveled when generating a given image data set to be incorporatedin the reconstruction of image 206, and can thereby accurately generatescale 207 in reference to the reconstructed image 206. In other modes ofaccurately generating scale 207, pull-back device 206A can include adevice for directly measuring the distance traveled by dilator 41 duringthe pull-back, for example by detecting revolutions of a roller wheel ofknown circumference, or any other suitable means, and can communicatetraveled distances to processor 201 that correlate to images acquired.Alternatively, such a direct measuring device can be provided in aseparate position-tracking device 212 which communicates similarinformation to processor 201 concerning dilator 41 shaft travel distanceduring image acquisition via connection 213. As another alternative,during pull-back, a user can manually communicate shaft travelincrements to processor 201 during image capture while watching markingfeature 47A as it moves past skin level or another reference point.These or other measures for accurately associating scale 207 with image206 can be used.

In certain embodiments, a graphical image 210 having features generallycorrelating to those of dilator 41 or the other device in use isdisplayed in association with image 206, potentially also in combinationwith scale 207. The graphical image 210 can include a graphicalrepresentation 211 of the IVUS probe 44, the distal tip of the device inuse, and/or other device features. The position and movement of theimage 210 relative to image 206 can be correlated to the position ofdilator 41 (or the other device in use) within the vessel 50. This canbe accomplished by inputting to processor 201 information related toshaft travel of dilator 41 during the procedure, starting from a knownreference point which may for example be manually inputted by a userbased upon visual observation of marking feature 47A relative to skinlevel or another reference point, and/or may be a direct continuation ofthe above-described positional tracking of the device 41 during thepull-back/image acquisition phase, for which the original positionalinput information from the user at the start of pull-back may continueto serve as a known reference point. To track shaft travel, devices fordirectly measuring shaft travel (e.g. as a part of the pull-back device206A or a separate position-tracking device 23), or manual entry by auser, can be used, as discussed above.

In a different mode, sequential images that continue to be acquired byIVUS probe 41 during the procedure can be compared, using an appropriatealgorithm and processor 201, to prior-acquired images obtained togenerate image 206. The newly-acquired images can then be registered toprior-acquired images of known position along image 206, and thegraphical image 210 can be positioned accordingly, e.g. by aligninggraphical IVUS probe image 211 with the registered prior-acquired image.

System 200 can also include an external ultrasound imaging probe 214(e.g. a transdominal probe) connected to processor 201 via transmissionconnection 215. Alternatively or in addition to graphical images 207and/or 210 discussed above, real-time external ultrasound images can bepositionally registered to prior-acquired and generated IVUS image 206and displayed therein or adjacent thereto, via appropriate fiduciarypoints established during the generation of IVUS image 206, for exampleby fixing the position of probe 214 during the procedure and acquiringfiduciary points during the pull-back operation, such as the location ofthe starting and finishing positions of an externally-imaged echogenicmarker (e.g. 45, FIG. 2) respectively at the start and end of thepull-back to generate image 206. In this manner, historic IVUS data andreal time external ultrasound data can be together used to guide adevice delivery or retrieval operation. Of course, real-time IVUS dataand images can also be used in conjunction with the historic IVUS dataand real time external ultrasound data.

The display 204 can also include patient-specific information 216 anddate/time information 217, as well as appropriate image descriptors 218and 219, or other standard system performance or setting information.

In still further embodiments of the invention, systems and methods asdescribed above which employ an ultrasound-emitting IVUS probe on apercutaneously-introduced device, can be used in conjunction with anexternal (e.g. transabdominal) ultrasound unit that is tuned to receivean ultrasound signal from the IVUS probe, and thereby detect thelocation of the IVUS probe as an “active” ultrasound marker in thesystem, or detect the location of a separate echogenic marker(s) on theintroduced IVUS device or neighboring devices based upon the reflectionby the separate marker(s) of the internally-generated IVUS signal. Inthis fashion the relative location of portions of the introduceddevice(s) can be detected with external ultrasound based on theIVUS-probe-generated, and potentially reflected, ultrasound signal. Inaddition or alternatively, the internally-generated IVUS probe signalcan be received by the external ultrasound unit and processed to developimages of biological structures, thus providing an “inside out”ultrasound image generation system. In some embodiments, the externalreceipt and processing of the signals from the IVUS probe can beaccomplished using an external ultrasound unit also used simultaneouslyor intermittently to emit and detect reflected ultrasound fordevelopment of ultrasound images, as discussed hereinabove.Alternatively, separate external ultrasound units can be used, one tunedto detect the IVUS probe-generated signals, and one functioning togenerate images of biological structures and potentially other featuresof the introduced device from externally-generated ultrasound. Incertain modes of practice, images or corresponding signals generatedfrom both ultrasound emitted by the internal IVUS probe and by anexternal unit can be used together, either displayed as separate imagesto a user or processed and combined using an algorithm (e.g. withregistration) to generate a single, enhanced image for display. Suchprocessing can be achieved using a computer processor as describedherein. Systems and methods as here described having images developedusing IVUS probe-generated ultrasound that is detected externally, aloneor in combination with externally-generated ultrasound, form additionalembodiments of the invention whether used with the specific systemsdescribed in conjunction with the drawings above, or otherwise.

It will be understood that although embodiments described herein are attimes discussed in connection with the delivery of, or features of, avascular filter and related sheath and/or catheter deployment devices,embodiments of the invention can likewise involve the delivery of, andfeatures of, other percutaneously-deliverable vascular devices such asstents, stent valves, occluders, embolization devices, anastomosisdevices, and the like. These and other permutations will be within thepurview of those of ordinary skill in the art given the teachingsherein.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. Recitation of ranges of values herein are merely intended toserve as a shorthand method of referring individually to each separatevalue falling within the range, unless otherwise indicated herein, andeach separate value is incorporated into the specification as if it wereindividually recited herein. All methods described herein can beperformed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context. The use of any and allexamples, or exemplary language (e.g., “such as”) provided herein, isintended merely to better illuminate the invention and does not pose alimitation on the scope of the invention unless otherwise claimed. Nolanguage in the specification should be construed as indicating anynon-claimed element as essential to the practice of the invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention. Ofcourse, variations of those preferred embodiments will become apparentto those of ordinary skill in the art upon reading the foregoingdescription. The inventors expect skilled artisans to employ suchvariations as appropriate, and the inventors intend for the invention tobe practiced otherwise than as specifically described herein.Accordingly, this invention includes all modifications and equivalentsof the subject matter recited in the claims appended hereto as permittedby applicable law. Moreover, any combination of the above-describedelements in all possible variations thereof is encompassed by theinvention unless otherwise indicated herein or otherwise clearlycontradicted by context. In addition, all publications cited herein areindicative of the abilities of those of ordinary skill in the art andare hereby incorporated by reference in their entirety as ifindividually incorporated by reference and fully set forth.

1. A retrievable vascular filter, comprising: a filter structureconfigured to trap embolic matter in a vascular vessel; a retrievalstructure connected to the filter structure, for retrieval of thevascular filter from the vessel; a first echogenic marker on the filter;and a second echogenic marker on the filter; wherein the first andsecond echogenic markers are operable to generate discrete, spacedultrasound images of the first and second echogenic markers demarking aretrieval structure capture zone between the first and second echogenicmarkers.
 2. The filter of claim 1, which is a vena cava filter.
 3. Thefilter of claim 1, wherein said distance is greater than 3 mm.
 4. Thefilter of claim 1, wherein said distance is in the range of 4 mm to 10mm.
 5. The filter of claim 1, comprising a filter hub, and wherein thefirst echogenic marker is on the hub, and the second echogenic marker ison the retrieval structure.
 6. The filter of claim 1, also comprising atleast a third echogenic marker, the third echogenic marker positioned onthe filter structure.
 7. The filter of claim 1, wherein the filterstructure comprises a plurality of struts.
 8. The filter of claim 1,wherein the retrieval structure comprises a hook.
 9. A method for thecapture of a vascular filter positioned within avascular vessel of apatient, comprising: introducing a snare device through a percutaneousaccess site spaced from the vascular filter; advancing the snare devicethrough the vascular system toward the vascular filter; visuallyobserving an ultrasound-generated image of a first echogenic marker onthe vascular filter; visually observing an ultrasound-generated image ofa second echogenic marker on the vascular filter, the second echogenicmarker longitudinally spaced a distance from the first echogenic marker;visually observing an ultrasound-generated image of a third echogenicmarker within a capture zone between the first and second echogenicmarkers, the third echogenic marker on the snare device; and closing asnare loop of the snare device within the capture zone so as to capturethe vascular filter.
 10. The method of claim 9, wherein the vascularfilter is a vena cava filter.
 11. The method of claim 9, wherein saiddistance is greater than 3 mm.
 12. The method of claim 9, wherein saiddistance is in the range of 4 mm to 10 mm.
 13. The method of claim 9,wherein said visually observing an ultrasound image of the thirdechogenic marker comprises visually observing a transabdominal-generatedultrasound image.
 14. The method of claim 9, wherein said visuallyobserving an ultrasound-generated image of the first echogenic markercomprises visually observing an intravenous ultrasound-generated imageof the first echogenic marker.
 15. The method of claim 9, wherein saidvisually observing an ultrasound-generated image of the second echogenicmarker comprises visually observing an intravenous ultrasound-generatedimage of the second echogenic marker.
 16. The method of claim 9, whereinsaid visually observing an ultrasound-generated image of the firstechogenic marker comprises visually observing both an intravenousultrasound-generated image of the first echogenic marker and an externalultrasound-generated image of the first echogenic marker.
 17. The methodof claim 16, wherein said visually observing an ultrasound-generatedimage of the second echogenic marker comprises visually observing bothan intravenous ultrasound-generated image of the second echogenic markerand an external ultrasound-generated image of the second echogenicmarker.
 18. A system for delivering a vascular filter to a target sitein a patient, the system comprising: a sheath introducible through apercutaneous access site of the patient, the sheath having an innerlumen and a distal tip, the sheath having an echogenic marker locatedproximate the distal tip and a first series of visible indicia occurringalong a first longitudinal region of the sheath, the first longitudinalregion positioned to include a location aligned with a reference pointexternal of the percutaneous access site when the distal tip of thesheath is at the target site; an intravascular ultrasound deviceconfigured for slidable receipt through the inner lumen of the sheathand having an intravascular ultrasound probe in a distal region thereoffor generating an ultrasound image signal for identifying the targetsite; and a filter introducer configured for slidable receipt throughthe inner lumen of the sheath, the filter introducer including a filterdelivery instrument and a vascular filter carried by the filter deliveryinstrument.
 19. The system of claim 18, wherein the vascular filterincludes a first echogenic marker, and a second echogenic markerlongitudinally spaced a distance from the first echogenic marker. 20.The system of claim 19, wherein the ultrasound probe is operable togenerate an ultrasound image signal having a longitudinal resolution,and wherein said distance is greater than said longitudinal resolution.21. The system of claim 19, wherein said distance is greater than 3 mm.22. The system of claim 19, wherein said distance is 4 to 10 mm.
 23. Thesystem of claim 19, wherein the filter includes a hub and plurality ofstruts emanating from the hub, and wherein the first echogenic marker isprovided on the hub.
 24. The system of claim 23, wherein the filterfurther includes a retrieval element emanating from the hub, and whereinthe second echogenic marker is provided on the retrieval element. 25.The system of claim 18, wherein the filter includes at least oneechogenic marker provided on at least one strut of the filter.
 26. Thesystem of claim 18, wherein the series of indicia includes scalemarkings.
 27. The system of claim 26, wherein said scale markingsregister distances from the distal tip of the sheath.
 28. A method fordelivering a vascular filter into the inferior vena cava of a patient,comprising: establishing a percutaneous access to the venous system ofthe patient; positioning a guidewire through the percutaneous access andinto the inferior vena cava of the patient; advancing an intravascularultrasound device over the guidewire through the percutaneous access andinto the inferior vena cava of the patient; identifying first and secondrenal veins of the patient in one or more images generated with theintravascular ultrasound device; positioning a distal end of theintravascular ultrasound device caudal to the first and second renalveins; advancing a sheath over the intravascular ultrasound device;positioning a distal end of the sheath proximate to the distal end ofthe intravascular ultrasound device with the distal end of theintravascular ultrasound device caudal to the first and second renalveins; visually determining that a visible marking along the sheath isat a reference point external of the patient with the distal end of thesheath positioned proximate to the distal end of the intravascularultrasound device; withdrawing the guidewire and intravascularultrasound device from the sheath while maintaining the position of thedistal end of the sheath caudal to the first and second renal veins withsaid visible marking at said reference point; advancing a filterdelivery catheter through the sheath while maintaining the position ofthe distal end of the sheath caudal to the first and second renal veinswith said visible marking at said reference point; and deploying avascular filter from the filter delivery catheter to a site of theinferior vena cava caudal of the first and second renal veins.
 29. Aretrievable vascular filter, comprising: a filter structure configuredto trap emboli in a vascular vessel; and at least one echogenic markerpositioned on the filter structure and positioned to appose a wall ofthe vascular vessel when the filter is deployed in the vessel.
 30. Thefilter of claim 29, wherein the filter structure comprises a pluralityof struts, and said at least one echogenic marker positioned on a strutof said plurality of struts.
 31. A vascular snare device, comprising: asnare catheter having a lumen; and a snare loop deployable into and fromsaid lumen; and an echogenic marker on said snare loop.
 32. The vascularsnare device of claim 31, also comprising an intravascular ultrasoundprobe located on a distal region of said snare catheter.
 33. Thevascular snare device of claim 31, wherein: said snare loop isdeployable from said lumen to an open condition; and said echogenicmarker is viewable with said probe with said snare loop in said opencondition.
 34. A method for the capture of a vascular filter positionedwithin a vascular vessel of a patient, comprising: introducing aretrieval device through a percutaneous access site spaced from thevascular filter; advancing the retrieval device through the vascularsystem toward the vascular filter; visually observing anultrasound-generated image of a first echogenic marker on the vascularfilter; visually observing an ultrasound-generated image of a secondechogenic marker on the vascular filter, the second echogenic markerlongitudinally spaced a distance from the first echogenic marker;visually observing an ultrasound-generated image of a third echogenicmarker within a capture zone between the first and second echogenicmarkers, the third echogenic marker on the retrieval device; andactuating the retrieval device within the capture zone so as to capturethe vascular filter.
 35. A method for confirming placement of a vasculardevice implanted in a vascular vessel, comprising: advancing a catheterhaving an IVUS probe beyond the implanted device; pulling the catheterback to capture IVUS data; and generating an IVUS image from the IVUSdata, the IVUS image showing the implanted device and one or moreadjacent anatomical landmarks.
 36. The method of claim 35, wherein thevascular device is a vena cava filter and the vascular vessel is a venacava.
 37. The method of claim 36, wherein the one or more adjacentanatomical landmarks include at least one renal vein and an ileo-cavaljunction.
 38. The method of, claim 35 wherein the image depicts firstand second ends of the implanted device.
 39. A method for maintaining apatient medical record, comprising electronically storing an imagegenerated by a method of claim 35 in a database containing the patientmedical record.
 40. A method for delivering a vascular filter into theinferior vena cava of a patient, comprising: percutaneously advancing asheath through a percutaneous access site so as to position a distal endof the sheath to a target position within the inferior vena cava of apatient, said advancing conducted at least partially under ultrasoundimaging guidance; engaging a reference marker device on the sheathproximate to skin level on the patient; deploying a vascular filter outof the sheath and into the inferior vena cava of the patient.
 41. Amethod according to claim 40, further comprising: positioning aguidewire through the percutaneous access site and into the inferiorvena cava of the patient; advancing an intravascular ultrasound deviceover the guidewire through the percutaneous access site and into theinferior vena cava of the patient; identifying first and second renalveins of the patient in one or more images generated with theintravascular ultrasound device; positioning a distal end of theintravascular ultrasound device caudal to the first and second renalveins; advancing the sheath over the intravascular ultrasound device;positioning a distal end of the sheath proximate to the distal end ofthe intravascular ultrasound device with the distal end of theintravascular ultrasound device caudal to the first and second renalveins; visually determining that the reference marker device is at areference point external of the patient with the distal end of thesheath positioned proximate to the distal end of the intravascularultrasound device; withdrawing the guidewire and intravascularultrasound device from the sheath while maintaining the position of thedistal end of the sheath caudal to the first and second renal veins withsaid visible marking at said reference point; advancing a filterdelivery catheter through the sheath while maintaining the position ofthe distal end of the sheath caudal to the first and second renal veinswith said visible marking at said reference point; and deploying avascular filter from the filter delivery catheter to a site of theinferior vena cava caudal of the first and second renal veins.
 42. Amethod for delivering a vascular implant to a vascular site of apatient, comprising: percutaneously advancing a delivery device toposition the delivery device to a target position within the vasculatureof a patient, said advancing conducted at least partially underultrasound imaging guidance; engaging a reference marker device on thedelivery device proximate to skin level on the patient; and deploying avascular implant from the delivery device and into the vascular systemof the patient.
 43. The method of claim 42, also comprising: positioningan ultrasound probe of an intravascular ultrasound imaging deviceproximate to the target position; advancing the delivery device over theultrasound imaging device to position a distal end of the deliverydevice proximate to a distal end of the intravascular ultrasound imagingdevice at the target position; with the distal end of the deliverydevice positioned proximate to the distal end of the intravascularultrasound imaging device, performing said engaging step; withdrawingthe intravascular ultrasound imaging device from the delivery devicewhile maintaining the position of the distal end of the delivery deviceat the target position; advancing a vascular implant through thedelivery device while maintaining the position of the distal end of thedelivery device at the target position; and deploying the vascularimplant from the delivery device.
 44. The method of claim 43, whereinthe delivery device is a sheath or catheter having a lumen.
 45. Themethod of claim 43, also comprising: visually detecting the positioningof the distal end of the delivery device proximate to the distal end ofthe intravascular ultrasound imaging device, said visually detectingincluding detecting a change in an image generated by the ultrasoundprobe.
 46. The method of claim 45, wherein said change is generated byan element of the delivery device reaching a position of at leastpartial alignment with said ultrasound probe.
 47. The method of claim46, wherein said element is a metallic marker.
 48. A system useful forimplanting a vascular device, comprising: a dilator for percutaneousintroduction into a patient, the dilator having a lumen and anintravascular ultrasound probe in a distal region thereof for generatingultrasound image data; a wire guide device receivable through thedilator lumen; and a delivery device receivable over the dilator. 49.The system of claim 48, wherein the delivery device is a catheter orsheath.
 50. The system of claim 48, wherein the delivery device has anechogenic marker in a distal region thereof.
 51. The system of claim 50,wherein the echogenic marker is also a fluoroscopic marker.
 52. Amedical device, comprising: a vascular snare including an elongate shafthaving an internal lumen and a snare loop; and wherein the snare loopincludes an echogenic marker and/or the elongate shaft has an ultrasoundprobe positioned in a distal region thereof.
 53. The medical device ofclaim 52, wherein the snare loop includes an echogenic marker andwherein the elongate shaft has an ultrasound probe positioned in adistal region thereof.
 54. The medical device of claim 53, wherein theechogenic marker is positioned on the snare loop and the snare loopdeploys to a configuration such that at least a portion of the echogenicmarker can be imaged using an ultrasonic signal generated with theultrasound probe.
 55. A system for delivering a vascular implant to avascular site of a patient, comprising: a percutaneous delivery devicefor delivering a vascular device; a reference marker device engageableon a portion of the delivery device that remains external of thepatient.
 56. The system of claim 55, also comprising an intravascularultrasound imaging device.
 57. The system of claim 55, wherein thedelivery device is a catheter or sheath.
 58. The system of claim 55,wherein the delivery device has a visible marking feature that extendsat least partially upon said portion of the delivery device that remainsexternal of the patient, said marking feature located to include atleast a portion that occurs at skin level of the patient when saiddelivery device is positioned to a target position for delivery of saidvascular device.
 59. The system of claim 58, wherein said markingfeature demarks the distance from locations within the marking featureto a distal tip of the delivery device.
 60. The system of claim 55,wherein the reference marker device is selectively engageable anddisengageable on the delivery device.
 61. The system of claim 55,wherein the reference marker comprises a spring collar.
 62. The systemof claim 55, wherein the reference marker is frictionally engageable onthe delivery device.
 63. A system for ultrasound guidance, comprising: acomputer processor for receiving signal data from an intravascularultrasound probe and generating ultrasound images using the signal data;a visual display device; and said computer processor and display deviceoperable to display two-dimensional, real time images generated usingthe signal data simultaneously with a three-dimensional image generatedfrom prior-acquired intravascular ultrasound image signal data.
 64. Thesystem of claim 63, wherein the three-dimensional image is generated byreconstructing a plurality of previously-acquired two-dimensional,cross-sectional image data sets from the probe
 65. The system of claim63, wherein the display also includes a reference scale and/or graphicalimage.